Process for forming feltable bituminous pulps



Patented Feb. 10,- 1931 UNITED STATES PATENT orrlca CHARLES L. KELLER, OF CINCINNATI, OHIO, ASSIGNOR TO THE RICHARDSON COMPANY, OF IIOGKLAND, OHIO, A CORPORATION OF OHIO PROCESS FOR FORMING FELTAIBLE BITUMINOUS PULPS 2N0 Drawing. 7

My invention is concerned with the production of pulps of fibrous material, suitable for felting upon a screen, in which bituminous material exists in minute uncoated particles in stable suspension. Its primary object is the provision of a new process of form.- ing such pulps, characterized by a number of operating advantages which will be set forth hereinafter or will be apparent to one skilled in the art upon reading these specifications.

Briefly in my process I take fibrous mate rial such as waste papers, pulp laps, cotton or the like, and after a pre-pulping operation in which they are reduced at least to half stock, I thicken the resulting semi-pulp. The thickened material, the characteristics of which will be hereinafter more fully described, I transfer to a mixing device where I incorporate into it bituminous material. Thereafter depending upon the condition of the mixed mass I may transfer it to a different type of mixing machine, there diluting it with water and afterwards placing it in a paper mill beater. After beating, the stock may be jordaned if necessary and then run over a paper making machine of any desired type.-

In copending applications of Harry G. Fisher, Ser.' No. 314:,55 1 filed Oct. 23, 1928,

and Earl P. Stevenson and Harry A. Buron,

Ser. No. 316,611 .filed Nov. 1, 1928, methods of making bituminous pulps have been described which comprise What I term premixing, i. e. bringing about an association of fibrous material and bituminous material before the combined or mixed mass is beaten to fit it for felting. My invention contemplates in a process of making a bituminous pulp, a pre-beating operation which comes before the premixing operation hereinabove referred to.

Preferably I carry on the pre-beating operation in what is known as a breaker beater,

,\ although other types of fiber liberating mechanisms are also serviceable. beater, the stock is semi-pulped and is brought into a water suspension forming what is known as half stock. I have found that prebeating to this extent is suflicient for excellent commercial results, although it will be clear that the fiber liberation and refining in the Application filed May 20,

In a breaker.

1929. Serial No. 364,704.

pre-beating step may be carried on to any extent desired. My object in preheating fibrous material is to liberate the fibers at least in part'so as to facilitate subsequent operations. Another object of the pre-beating is to reduce the stock to a compact, easily handled form such that it can be introduced into a mixing device with the desirable convenience and speed. .As hereinafter to be explained, a type of mixing device which I prefer to use is the Banbury mixer, which is a pressure mixer equipped with a ram operating in the feeding neck, which is generally of constricted dimensions. A considerable problem is involved in feeding fibrous materials rapidly enough into a Banbury machine. The feeding operation may be speeded up by baling or bundling fibrous materials into small parcels of suitable size to enter the neck; but this is cumbersome, costly and inconvenient. WVaste papers or other fibrous material may be shredded to a size suflicient for entering the neck; but when ity is shredded, it is bulked and remains inconvenient and slow in handling. The introduction of stock in a form in which it may easily be handled as a soft plastic mass is highly advantageous in that it permits the rapid charging of the mixer and the realization of one of the chief advantages of pressure mixers, namely, diminished time cycle. It is also important commercially to pre-beat the fibers to permit more rapid incorporation of the bituminus material therein, to obviate the necessity of any pulping or semipulping operation in the mixer, to realize the full benefit of the shortened time cycle of pressure mixers, and to facilitate the production in the mixer of a finished premixed stock which may be in semi-pulped or slush pulp form. g

After the pre-beating I thicken the stock in a concentratorto reduce the amount of water in the half stock. This gives a material which does not contain an excess of water, whichis more easily handled, and which also conserves space because it is not bulked by an undesirable amount of'liquid. The object of a mixing operation is to bring about an association of bitumen with fibers; and this association Within certain limits is facilitated by. a beaver consistency of the stock. This consistency in the thickened pulp will vary with the desired type of bituminous pulp to-- ward which the process is directed, a lighter consistency being satisfactory with soft bitumens, whereas harder bitumens will generally require a heavier consistency.

A consistency suitable for ordinary work is one in which the thickened mass is plastic in its character, and capable of being handled as a heavy mush rather than as a liquid. In this form it mayconvcniently be fed into any type of mixer rapidly; and I am able by my process to reduce the time consumed in the operation of charging a mixer with a restricted charging neck, to a minimum.

As indicated the type of mixing device employed may vary. A mixer of the Werner Pfleiderer type may be employed, or a mixer fitted with a pressure ram, and of the latter I prefer to use a type known as the Banbury and described in Letters Patent of the United States No. 1,200,070, issued October 3, 1916. Theobject of the mixing operation is to associate the bitumen with the fibrous material as rapidly as possible. With the pressure type of mixer the time cycle may be extremely short whereas with the open type, it is more lengthy. It is somewhat easier to control the consistency of stock in an open mixer by the addition of water; but the mechanical action is not so intense and the mixing operation takes longer. Into the mixer, to be mixed with the fibrous material, various bituminous substances can be used, with or without additional pulps or unpulped fibrous materials such as rags, pulp laps, or the like. The operation of the mixer may be controlled to deliver a stock which may be referred to as a slush pulp on the one hand or a more or less hard plastic material on the other, depending upon the amount of water present, together with theamount of bituminous substance with relation to the fibrous material.

Where the first mixer is used to deliver a material which is not in slush pulp form, it will be found advantageous to transfer the mixed mass to a second mixer where it is broken down in the presence of water into smaller masses suitable for introduction into the beater.

The material in suitable form for beating is introduced into a hollender or other fiber liberating device and beaten to fit it for felting upon a screen. This is usually accompanied by further dilution befone the mass is transferred to arefining device such as a jordan. The beaten stock is then transferred, having been diluted to proper consistency, to the vats of a cylinder mold machine or of a Fourdrinier paper machine and there felted into a sheet, dried and finished.

The amount of bitumen may vary within wide limits but I have worked with bituminous material up to by weight of the total solids in the pulp. During the mixing operation, the bitumen will be heat softened and may be rendered liquid. Various modifications in my process may be made without departing from the spirit of my invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is

1. That process of producing a bituminous pulp which comprises pre-beatlng fibrous material to form a half stock, concentrating the half stock to bring it to an easily handled plastic stage, transferring the concentrated stock to a mixer, adding bituminous material and premixing, afterward, transferring the premixed stock to a beater and beating it to fit the fibers for felting.

2. That process of producing bituminous pulp which comprises pre-beating the ma terial in water suspension, concentrating the pulp so formed to a plastic condition, premixing with the pulp so formed a bituminous substance, and beating and refining the premixed stock.

3. That process of preparing a bituminous pulp which comprises pre-beating a fibrous material to form a pulp, concentrating the said pulp to a plastic mass, transferring the said mass to a mixer, and pre-mixing therewith a bituminous material while maintaining the water content of said mass, transfer.- ring the premixed mass to a heater and di-' lutlng and beating the same, thereafter further diluting the pulp'so formed and felting it upon a screen.

4. That process of producing a bituminous pulp which comprises beating fibrous material in a breaker beater to produce a half stock, concentrating the half stock to produce amushy pulp, rapidly chargin the said mushy pulp with a quantity of fiituminous material into a pressure mixer and premixing the material therein under pressure, thereafter transferring the mixed mass to a second mixer, adding water and reducing to a semi-suspension suitable for beating, trans.- ferring the semi-suspension to a beater and beatin the stock with further dilution to fit it for elting.

5. That process of producing a bituminous pulp which comprises pre-beating fibrous material to form half stock, concentrating the said half stock and transferring it toa mixer, mixing it with a quantity of bituminous material to form a lumpy mass, transferrin the lumpy mass to a second mixer and brea ing it down in the presence of water, transferring the broken down stock to a beater and heating it into a pulp suitable for felting.

6. That process of producing a bituminous pulp which comprises pre-beating fibrous material, concentrating the pulp so formed, premixing it in a mixer with bituminous material to form a lumpy mass, breaking down the lumpy mass by mixing it with water,

transferring the broken down mass to a beater and beating it with further dilution, transferring the beaten stock to a jordan and refining it with further dilution, and felting the pulp so formed upon a screen.

7 That process of forming a bituminous pulp which comprises the steps of pre-beating and concentrating a fibrous stock, premixing the said stock with a bituminous substance, breaking down the premixed stock with water, heating, jordaning and diluting the stock to fit it for felting upon a screen.

8. That process of producing a pulp containing a heat plastic substance which comprises preheating fibrous material to form half stock, concentrating the half stock and transferring it to a mixer, mixing it with a quantity of heat plastic substance to form a lumpy mass, transferring the lumpy mass to a second mixer and breaking it down in the presence of water, transferring the broken down stock to a beater and heating it into a pulp suitable for felting.

9. That process of forming a pulp containing a heat plastic substance which comprises the steps. of pre-beating and concentrating a fibrous stock, premixing the said stock with a bituminous substance, breaking down the premixed stock with water, beating, jordaning and diluting the stock to fit it" for I felting upon a screen. CHARLES L. KELLER. 

